Association of a specific chromosomal abnormality with a specific tumor type is well established and may reflect mechanisms of oncogenesis peculiar to that tumor. Alternatively, it may be that these associations reflect the particular differentiated state of the malignant cell, consistent with the model that rearrangements occur only within chromatin in an "active" configuration. We have previously demonstrated this fact for erythroleukemias in which translocations can often be found to involve the chromosomal bands on which are located the globin gene families. We have developed a long term research program involved in discovering the importance of the consistent involvement of the immunoglobulin or T-cell receptor gene encoding regions in the translocations observed in B- and T-cell tumors respectively. Over the past year, using this concept as a predictive and testable hypothesis, we have and are continuing to investigate the relationship of specific chromosomal abnormalities to certain tumors. Our focus at present is on diseases of the hematopoietic system. This research program requires expertise in a number of distinct biological techniques. We have established this technical expertise which includes 1) our capability to grow and maintain a wide array of primary cells and cell lines 2) our facility in doing basic cytogenetic analyses, as well as the more involved procedure of chromosome in situ hybridization and, 3) our constantly updated ability to utilize the very newest of molecular biological techniques to clone, map, sequence and perform expression studies on DNA segments of interest.